spi: use to_spi_device

Use to_spi_device() instead of open-coding it.

Signed-off-by: Geliang Tang <geliangtang@163.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index e2415be..7082852 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -84,8 +84,7 @@
 					 struct device_attribute *attr,	\
 					char *buf)			\
 {									\
-	struct spi_device *spi = container_of(dev,			\
-					      struct spi_device, dev);	\
+	struct spi_device *spi = to_spi_device(dev);			\
 	return spi_statistics_##field##_show(&spi->statistics, buf);	\
 }									\
 static struct device_attribute dev_attr_spi_device_##field = {		\